View an important notice for this dataset
URL: https://d2pn8kiwq2w21t.cloudfront.net/documents/ProductSpec_DSWX_URS309746.pdf
Issue: Cloud dilation and cirrus cloud labeling may obscure valid water detection. Description: The DSWx WTR layer inherits labels for cloud, cloud shadow, and adjacent to cloud from the input HLS Fmask. The current HLS implementation of Fmask does not distinguish cirrus from other cloud types and pixels labeled as clouds are dilated (buffered) by a large distance to conservatively remove reflectance values that might be errant. However, the DSWx algorithm often correctly distinguishes inundated land ‘under’ these masked areas. Recommendation(s): If this issue is problematic and the application permits, users are advised to composite multiple days of DSWx WTR observations, taking the minimum non-zero value across all dates in the composite period. Should this prove inadequate or when specific dates are of interest, the DSWx WTR-2 layer is explicitly designed as a potential substitute for the WTR layer when snow/ice isn’t prevalent, but cloud masking is excessive. No cloud, cloud shadow, or adjacent to cloud masking is applied to create WTR-2. See the Product Specification and Algorithm Theoretical Basis Documents for more information on DSWx band characteristics and purposes. Issue: Occasional erroneous snow/ice labels. Description: The DSWx WTR layer inherits snow/ice classification directly from the input HLS Fmask. Occasionally, Fmask misclassification occurs over water with atypical coloration due to dissolved solids, high concentrations of sediment or where waves are breaking along coastline segments. Recommendation(s): HLS Fmask based labels for snow/ice have not been applied to the DSWx WTR-2 layer. When snow/ice labeling is observed in the DSWx WTR layer and they are not expected, users are advised to check the DSWx WTR-2 layer and consider whether this layer or a combination of it and just cloud-related labels might be applicable to their study area and application. See the Product Specification Document for a description of applicable class values in the DSWx CLOUD layer. Issue: Occasional unmasked clouds over ocean. Description: The DSWx WTR layer inherits labels for cloud, cloud shadow, and adjacent to cloud from the input HLS Fmask. Occasionally, the DSWx algorithm will classify as ‘not water’, clouds present over water that Fmask failed to detect. This visual artifact does not impact DSWx performance over dominantly land areas. Recommendation(s): If this artifact unduly affects product utility and simple masking of ocean areas are not appropriate, the user is advised to temporally composite DSWx, taking the lowest non-zero value in each composite period. See the Product Specification Document for a description of applicable class values in the DSWx CLOUD layer.
About this Resource
| Last updated | unknown |
|---|---|
| Created | unknown |
| Name | View an important notice for this dataset |
| Format | PDF File |
| License | License not specified |
| Created | 3 months ago |
| Media type | application/pdf |
| has views | False |
| id | 244a4016-446a-48e4-a23b-deb6a713a65d |
| metadata modified | 3 months ago |
| package id | 99beda62-c63b-4fbe-843e-a4cb0af418f2 |
| position | 13 |
| state | active |
| tracking summary | {'total': 0, 'recent': 0} |